Datasheet
Table Of Contents
- List of Sections
- Table of Contents
- General Description
- Central Processing Unit (CPU)
- Pinout and Signal Description
- System Configuration
- Registers
- Operating Modes
- Resource Mapping
- Bus Control and Input/Output
- Resets and Interrupts
- Voltage Regulator (VREG)
- Flash EEPROM 256K
- EEPROM 4K
- Port Integration Module
- Clocks and Reset Generator (CRG)
- Pulse Width Modulator (PWM)
- Enhanced Capture Timer (ECT)
- Serial Communications Interface (SCI)
- Serial Peripheral Interface (SPI)
- Inter-IC Bus (IIC)
- MSCAN
- Analog to Digital Converter
- Byte Data Link Controller Module
- Contents
- Overview
- Features
- Block Diagram
- Register Map
- Functional Description
- Register Descriptions
- External Pin Descriptions
- Reset Initialization/Basic Operation
- Transmitting A Message
- Receiving A Message
- Transmitting An In-Frame Response (IFR)
- Receiving An In-Frame Response (IFR)
- Special BDLC Operations
- Modes of Operation
- Interrupt Operation
- Low Power Options
- Background Debug Module (BDM)
- Breakpoint (BKP) Module
- Revision History
- Glossary
- Literature Updates

Central Processing Unit (CPU)
MC9S12DP256 — Revision 1.1
Central Processing Unit (CPU)
Programming Model
STAR12 CPU registers are an integral part of the CPU and are not
addressed as if they were memory locations.
Figure 1 Programming Model
Accumulators
A and B are general-purpose 8-bit accumulators used to
hold operands and results of arithmetic calculations or data
manipulations. Some instructions treat the combination of these two
8-bit accumulators as a 16-bit double accumulator (accumulator D).
7
15
15
15
15
15
D
IX
IY
SP
PC
AB
0
0
0
0
0
0
70 8-BIT ACCUMULATORS A & B
16-BIT DOUBLE ACCUMULATOR D
INDEX REGISTER X
INDEX REGISTER Y
STACK POINTER
PROGRAM COUNTER
OR
NSXH I ZVC CONDITION CODE REGISTER
STOP DISABLE (IGNORE STOP OPCODES)
CARRY
OVERFLOW
ZERO
NEGATIVE
IRQ INTERRUPT MASK (DISABLE)
HALF-CARRY FOR BCD ARITHMETIC
XIRQ INTERRUPT MASK (DISABLE)
Freescale Semiconductor, I
Freescale Semiconductor, Inc.
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